1. Field of the Invention
The present invention relates to an image processing method which analyzes images of the same objects in a scene taken simultaneously from different viewpoints by two or more image pick-up devices, and thereby estimates the real surface of the objects in three-dimensional space, and obtains information thereon.
2. Description of Related Art
Stereoscopy is known as a method for obtaining three-dimensional (or distance) information of a scene using the images taken by two or more image pick-up devices. The distances are computed according to the principle of triangulation using the corresponding points between the images. There are two common approaches for finding corresponding points between the images: the area-based stereo and the edge-based stereo.
The area-based stereo binds the corresponding points between the images by computing local correlations between the images and can give the dense distance map of the scene in the case where the surface are covered with textures. However, it cannot be applicable in the case where the surfaces are uniform, that is, there is no texture on the surfaces.
The edge-based stereo first detects edges in each image by computing intensity gradient at each point in the image, and then find the corresponding edges between the images.
This approach, however, computes the distances only of the edges but gives no distance information of the inner points on the surfaces of the objects in the scene. Usually, a surface interpolation technique is used to fit a smooth surface bounded by the edges. However, it is not applicable when it is not known in advance which side of the edge is the actually existing surface or if both sides are the actually existing surfaces. Otherwise false surfaces are created by the interpolation.